An actuator is a mechanism often used to lift or move an object or to clamp an object to prevent motion. An actuator may introduce linear or non-linear motion. Examples of actuators include hydraulic cylinders, pneumatic cylinders, electrical motors, and etc. Actuators are used in many applications, including construction equipment, engineering vehicles and manufacturing machinery. For example, the hydraulic cylinder is a mechanical actuator that may provide a unidirectional force through a unidirectional stroke. The hydraulic cylinder consists of a cylinder in which a piston connected to a rod moves back and forth.
Actuators suffer from disadvantages or drawbacks associated with the misalignment of the load in relation to the centerline or axis of the cylinder. This misalignment may be the result of setting poorly balanced or off-center loads with respect to the centerline or axis of the cylinder. This may occur for example, when the rod contacts an uneven surface. This problem may cause damage to the cylinder and the cylinder may ultimately fail.
Much effort has been made by manufacturers of hydraulic cylinders to reduce or eliminate the side loading of cylinders created as a result of misalignment. It is almost impossible to achieve perfect alignment of a hydraulic cylinder, even though the alignment of the cylinder has a direct impact on the longevity of the hydraulic cylinder. Actuators for many applications are custom made and expensive so prolonging their life and operation can represent significant savings.
Many hydraulic cylinders involve an internal piston that is moved back and forth along the length of the cylinder. An actuation rod is often attached to the cylinder and the rod moves in and out of the cylinder as the piston moves. The actuation rod is often connected to structure outside of the cylinder that moves when the rod moves. Often, a wiper is located near the end of the piston into which the rod enters. The wiper is used to clean the rod of dirt, debris, and any foreign matter before the rod enters the hydraulic cylinder.
Inside of the hydraulic cylinder is a seal that is often used to seal against the rod and prevent hydraulic fluid from the hydraulic cylinder from moving out the hydraulic cylinder along with the rod. However, a drawback of the seal is that the rod is dried once it moves past the seal and therefore is not lubricated as the rod moves past or rubs the structure of the hydraulic cylinder as it moves in and out of the cylinder.
A lack of lubrication along the rod, as it moves past the structure of the hydraulic cylinder, can create wear on the surface of the rod. This wear problem can be exacerbated when the rod is subject to side loads. Side loads may occur where forces acting on the rod in a direction not axial with the rod. These side loads can cause the rod to rub against the structure of the hydraulic cylinder as the rod moves in and out of the hydraulic cylinder.
Accordingly, it is desirable to provide a method and apparatus that provides lubrication for the rod.
These prior art methods and systems, however, have not sufficiently reduced or eliminated bending moments that cause stress on the rod and ultimately lead to rod failure. Therefore, there is a need for actuators that can operate to reduce bending moments that can potentially cause the cylinder assembly to fail.
The presently disclosed system and method is directed at overcoming one or more of these disadvantages in currently available actuators.